Chapter 5 The Periodic Table. History of the Periodic Table *By 1860 more than 60 elements were known Stanislao Cannizzaro (1826-1910) - Found a method.

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Presentation on theme: "Chapter 5 The Periodic Table. History of the Periodic Table *By 1860 more than 60 elements were known Stanislao Cannizzaro (1826-1910) - Found a method."— Presentation transcript:

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Chapter 5 The Periodic Table

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History of the Periodic Table *By 1860 more than 60 elements were known Stanislao Cannizzaro ( ) - Found a method to determine atomic mass Dimitri Mendeleev ( ) – “Father of the Periodic Table” -Made the first accepted Periodic Table -Noticed trends and left empty spaces for “missing” elements

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History of the Periodic Table Henry Moseley (1887 – 1915) – Found a method to determine atomic number (# of protons)

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Periodic Law Properties of elements are based on atomic number and valence electrons Modern Periodic Table -Arranged by atomic numbers so elements with similar properties fall in the same columns -Newest sections added: Lanthanides, Actinides, Noble Gases

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Blocks on the Periodic Table p block: -Group 17 = Halogens – Very reactive A halogen lamp also uses a tungsten filament, but it is encased inside a much smaller quartz envelope. Because the envelope is so close to the filament, it would melt if it were made from glass. The gas inside the envelope is also different -- it consists of a gas from the halogen group. These gases have a very interesting property: They combine with tungsten vapor. If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. This recycling process lets the filament last a lot longer. In addition, it is now possible to run the filament hotter, meaning you get more light per unit of energy. You still get a lot of heat, though; and because the quartz envelope is so close to the filament, it is extremely hot compared to a normal light bulb. (http://home.howstuffworks.com/question151.htm)home.howstuffworks.com/question151.htm

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Blocks on the Periodic Table p block: -Group 18 = Noble Gases – Very unreactive - They have a stable (full) valence octet -Many used in creating signs Neon signs are luminous-tube signs that contain neon or other inert gases at a low pressure. Applying a high voltage (usually a few thousand volts) makes the gas glow brightly. They are produced by the craft of bending glass tubing into shapes. A worker skilled in this craft is known as a glass bender, neon or tube bender. (http://en.wikipedia.org/wiki/Neon_sign)en.wikipedia.org/wiki/Neon_sign

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Periodic Properties (aka TRENDS) 5. Ionic Radius (Size of ion) Cation = LOST electron(s) Has POSITIVE charge SMALLER than the neutral atom – due to less electrons, so nucleus can pull better on each e - Potassium Atom = 19 protons and 19 electrons Potassium ION = 19 protons and 18 electrons Lost 1 electron Now ALL of these electrons get pulled in a little bit!

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Periodic Properties (aka TRENDS) 5. Ionic Radius (Size of ion) Anion = Gained electron(s) Has NEGATIVE charge Larger than the neutral atom – due to more electrons, so nucleus can’t pull as well on each e - The extra e-. Now all of the electrons move out a little bit.

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Example Questions 1.Which is smaller – C or O? 2.Which is larger – Be or Be +2 (Be ion)? 3.Which has a more exothermic electron affinity – Na or P? 4.Which has a more endothermic electron affinity – K or Cs? 5.Which has a higher ionization energy – Ga or Se? 6.Which has a higher electronegativity – F or Br?